1. Field of the Invention
The present invention relates generally to methods for fabricating a magnetic head read sensor, and more particularly to the use of a reactive ion milling process step to accurately fabricate a stencil for subsequently fabricating the central read sensor element of a magnetic head.
2. Description of the Prior Art
Magnetic heads for hard disk drives include a read sensor that detects data bits formed on a rotating hard disk. The data bits are written in narrow data tracks, and the read sensor is formed with a corresponding read track width for accurately reading the data bits in the data track. As the data areal storage density of hard disks increases, the data track width necessarily becomes narrower and the read track width of the magnetic head sensors must correspondingly decrease to properly read data from the narrower data track.
The standard method for fabricating a magnetic head sensor involves the deposition of a plurality of sensor layers upon a substrate, followed by the masking of desired portions of the sensor layers with a stencil or mask of the desired read track width. Thereafter, an ion milling step is conducted in which the stencil shields the desired central sensor layer portions and the unshielded sensor layer portions are removed. The fabrication of the stencil is therefore a significant step in the subsequent fabrication of the sensor. As the data track width of hard disks has decreased, necessitating a corresponding decrease in the read track width of the magnetic head sensor, the accurate fabrication of the sensor stencil has become an even more significant factor in the ion milling process that forms the sensor. It is therefore desirable to develop a sensor stencil fabrication process that accomplishes the creation of a more accurate stencil, such that magnetic heads having a narrow read track width can be accurately fabricated.